.banner{
    height: 500px;
}
.banner1{
    background: url("../img/banner.jpg");
    background-size: cover;
}
.banner2{
    background: url("../img/banner2.jpg");
    background-size: cover;
}
.banner3{
    background: url("../img/banner3.jpg");
    background-size: cover;
}
/**响应式**/
@media (max-width: 600px) {
    .banner{
        height: 230px;
    }
}

footer{
    background-color: rgba(238, 238, 238, 0.64);
    padding-top: 70px;
    padding-bottom: 70px;
    font-size: 14px;
}